1. Field of the Invention
The present invention relates to a hard multilayer coated product improved in wear resistance and self-lubricity and applicable to tools, metal molds and machine parts, and a process for producing the product.
2. Description of the Prior Art
There has heretofore been used a coating of TiC or TiN to improve the wear resistance of tools, molds and machine parts. In spite of its wear resistance, the titanium compound hard coating was poor in self-lubricity and often adhered with an active metal such as aluminum under a nonlubricating condition. On the other hand, hard amorphous carbon formed a self-lubricating hard coating but was insufficient in tight bonding to a substrate and liable to delaminate therefrom. The attempt to form a hard amorphous carbon coating on TiC or TiN was hardly successful since the coating peeled off from TiC or TiN during or immediately after the coating formation in most of the cases because of a high internal stress of the hard amorphous carbon and a poor compatibility thereof with TiC or TiN. The introduction of a layer containing TiC or other titanium compound as the intermediate layer between the hard amorphous carbon and TiC or TiN enables the laminate to be used for a light load application or an ornamental use. However, the tight bonding of the intermediate layer to the hard amorphous carbon is yet so insufficient that the laminate is impractical for an application where self-lubricity or wear resistance is required.